Conversion of olefins and paraffins to higher hydrocarbons

ABSTRACT

A process is provided for converting feedstock comprising C 2   +  olefins, C 2  -C 7  paraffins or a mixture thereof to conversion product comprising C 5   +  hydrocarbon compounds over a catalyst composition prepared by compositing a high-silica zeolite having a Constraint Index of from 1 to 12 with binder, followed by treating the composite under conditions effective for increasing the catalytic activity of the composition.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 573,776, filed Jan. 23, 1984, now U.S. Pat. No. 4,559,314,which is a continuation-in-part of U.S. patent application Ser. No.360,749, filed Mar. 22, 1982 abandoned, the entire contents of eachbeing incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to catalysis over a catalyst prepared by a methodfor increasing the catalytic activity of crystalline zeolites bytreatment with water. In particular, the invention relates to conversionof feedstock comprising C₂ ⁺ olefins and/or C₂ -C₇ paraffins to productcomprising C₅ ⁺ hydrocarbons.

THE PRIOR ART

Zeolite catalysts have become widely used in the processing of petroleumand in the production of various petrochemicals. Reactions such ascracking, hydrocracking, alkylation, dealkylation, transalkylation,isomerization, polymerization, addition, disproportionation and otheracid catalyzed reactions may be performed with the aid of thesecatalysts. Both natural and synthetic zeolites are known to be activefor reactions of these kinds.

Synthetic zeolites containing high proportions of silica relative toalumina have been developed and zeolites of this kind have shownthemselves to be useful. U.S. Pat. No. 3,702,886 to Argauer et aldiscloses a class of crystalline silicates designated ZSM-5 which havehighly advantageous properties. U.S. Pat. Nos. 3,941,871 and its ReissueNo. 29,948 to Dwyer et al disclose crystalline silicates which exhibit astructure, as evidenced by X-ray diffraction pattern, similar to that ofZSM-5 with high ratios of silica relative to alumina. Materials of thiskind are stated to exhibit low aging rates and to have low coke makingproperties when used in hydrocarbon processing.

Various treatments have been proposed in the past for modifying theactivity of the zeolites, either by reducing it when too active or byincreasing it when insufficient. One such treatment has been steamingand in the past it has generally been used to decrease the activity ofthe zeolite, as reported in "Fluid Catalytic Cracking with ZeoliteCatalysts", Venuto and Habib, Marcel Dekker Inc., N.Y., N.Y. 1979.

The reduction of activity is not, however, necessarily undesirablebecause it may in certain circumstances be accompanied by an improvementin other characteristics of the zeolite, for example, resistance toaging. This fact has been exploited in certain processes, for example,in the alkylation process described in U.S. Pat. No. 4,016,218, whichemploys a zeolite catalyst which has been subjected to a prior thermaltreatment either in an inert atmosphere or by steaming, to reduce itsactivity. The deactivation caused by the steam becomes more pronouncedat higher temperatures and with longer reaction times.

It has also been found that steaming may in certain instances havebeneficial effects upon the catalyst. U.S. Pat. No. 3,257,310, forexample, describes a method for preparing a cracking catalyst of highactivity and selectivity by steaming a zeolite for at least two hours ata specified temperature. The zeolites described in this patent includenatural zeolites such as mordenite and faujasite and synthetic zeolitessuch as zeolites X, Y and L.

U.S. Pat. Nos. 4,149,960 and 4,150,062 describe the use of water in thefeedstock during operation to reduce coking and aging rates. U.S. Pat.No. 3,546,100 describes a method for maintaining the selectivity of ahydrocracking catalyst by restricting the partial pressure of waterduring the hydrocracking operation.

U.S. Pat. No. 3,493,519 describes a method of producing hydrothermallystable cracking catalysts by calcining zeolite Y in the presence ofsteam, a process which was theorized to cause lattice aluminum defectswhich, after subsequent treatment by base exchange with ammonium salts,chelation and calcination in air produced the desired highly activeproduct.

U.S. Pat. No. 3,493,490 describes a method for restoring the activity toused catalyst by controlled treatment with anionic reagents includingwater at high temperatures, even with catalysts which had initially beensteamed to reduce their level of cracking activity, such as zeolites Xand Y.

U.S. Pat. No. 3,758,403 describes a method for cracking hydrocarbonfeedstocks using a mixture of zeolites including a ZSM-5 type zeoliteand a large pore zeolite such as zeolites X, Y or L or faujasite. Theselectivity of the catalyst is said to be improved by treatment withsteam which, if desired, may be carried out in the cracking unit itself.

In U.S. Pat. Nos. 3,960,978 and 4,021,502, conversion of C₂ -C₅ olefins,alone or in admixture with paraffinic components, into higherhydrocarbons over crystalline zeolites having controlled acidity isdisclosed. Processing techniques for conversion of olefins to gasolineand distillate are disclosed in U.S. Pat. Nos. 4,150,062, 4,211,640 and4,227,992. The above-identified disclosures are incorporated herein byreference.

Olefinic feedstocks may be obtained from various sources, includingfossil fuel processing streams, such as gas separation units, crackingof C₂ + hydrocarbons, coal byproducts, and various synthetic fuelprocessing streams. Cracking of ethane and conversion of conversioneffluent is disclosed in U.S. Pat. No. 4,100,218 and conversion ofethane to aromatics over Ga-ZSM-5 is disclosed in U.S. Pat. No.4,350,835. Olefinic effluent from fluidized catalytic cracking of gasoil or the like is a valuable source of olefins, mainly C₃ -C₄ olefins.

SUMMARY OF THE INVENTION

It has now been found that the degree to which the activity of thezeolites can be enhanced by steaming is increased if the zeolite issteamed in the presence of a binder for the zeolite. The binderpreferably used is alumina, either on its own or in the presence ofother porous matrix materials. It is believed that the steaming producesadditional stable active sites in the zeolite and that these additionalsites are responsible for the observed increase in activity.

A novel catalyst composition has been found. This composition comprisesan intimate admixture of a high silica crystalline zeolite and anactivating metal oxide such as alumina, the composite being treated atelevated temperature in the presence of water to substantially enhancethe catalytic activity.

The novel compositions are useful for hydrocarbon conversion.

DESCRIPTION OF PREFERRED EMBODIMENTS

The feedstock to the present process comprises C₂ -C₇ paraffins and/orolefins of at least two carbon atoms. Product of the present processcomprises C₅ ⁺ hydrocarbons. When the feedstock comprises paraffins,product comprises aromatics, e.q., benzene, toluene and xylenes, andconversion conditions include a temperature of from about 100° C. toabout 700° C., a pressure of from about 10 kPa to about 11000 kPa,preferably from 10 kPa to 7000 kPa, a liquid hourly space velocity(LHSV) of from about 0.1 hr ⁻¹ to about 500 hr⁻¹, preferably from 0.5hr⁻¹ to 400 hr⁻¹, and a hydrogen/hydrocarbon mole ratio of from 0 (noadded hydrogen) to about 20. Under these same conversion conditions, afeedstock comprising C₂ -C₇ olefins is converted to product comprisingaromatics, e.g., benzene, toluene and xylenes.

A feedstock to the present process may comprise primarily C₂ -C₇ olefinsfor conversion to gasoline and distillate products when the conversionconditions are tailored to be within the following ranges. In general,the temperature will be maintained at from about 190° C. to about 375°C., the pressure at from about 400 kPa to about 11000 kPa, preferablyfrom 400 kPa to about 7000 kPa, and the liquid hourly space velocity(LHSV based on feedstock olefin) at from about 0.3 to about 2,preferably from 0.5 to 2 hr⁻¹. Specifically when the present process isoperated in the distillate mode, the temperature will be from about 190°C. to about 315° C., the pressure from about 4200 kPa to about 11000kPa, preferably from 4200 kPa to 7000 kPa, and the LHSV from about 0.3to about 1.0 hr⁻¹, preferably from 0.5 to 1.0 hr⁻¹. When the presentprocess is operated in the gasoline mode, the temperature will be fromabut 230° C. to about 375° C., the pressure from about 400 kPa to about4700 kPa, preferably from 400 kPa to 3000 kPa and the LHSV from about0.3 to about 2.0, preferably from 0.5 to 2.0 hr⁻¹. The feedstocks,products, process conditions and other variables for conversion ofolefins to higher hydrocarbons are detailed in U.S. Pat. No. 4,456,779,incorporated entirely herein by reference.

The zeolites which are used in the present invention have a silica toalumina ratio of at least 100 and may be much higher. It has been foundthat the degree of enhancement in the activity of the zeolite becomesgreater as the silica to alumina ratio of the zeolite increases.Accordingly, the higher silica to alumina ratios above about 250:1 arepreferred. If possible, the ratio should exceed 500:1 and we have foundthat marked enhancement of activity is obtained at ratios over 1200:1,for example, 1600:1. The use of ratios even higher than this iscontemplated, going as high as 3200:1 or even higher. The silica toalumina ratio may be determined by conventional analysis. The term ratioas used herein represents, as closely as possible, the ratio in therigid anionic framework of the zeolite crystal i.e. the structural orframework silica:alumina mole ratio and is intended to exclude materialssuch as aluminum in binder or in another form within the channels of thezeolite. The ratio may be determined by conventional methods such asammonia desorption/TGA, or by other ion-exchange techniques. The ammoniadesportion/TGA technique is described in a paper by G. T. Kerr, whichappears in Thermochimica Acta, Volume 3, (1971), pp. 113-124.

Preferred zeolites may also be characterized by their Constraint Index,which is to be within the approximate range of 1 to 12. The ConstraintIndex is a measure of the constraint imposed by the crystal structure ofthe zeolite on the access by molecules of differing sizes to theinternal structure of the crystal. A measure of such constraint isdesired in order to obtain the desired conversions. It is sometimespossible to judge from a known crystal structure whether constrainedaccess of this kind exists. For example, if the only pore windows in acrystal are formed by 8-membered rings of silicon and aluminum atoms,molecules with a cross-section larger than normal hexane will beexcluded and the zeolite is not of the desired type. Zeolite havingwindows of 10-membered rings are preferred, although, in some instances,excessive puckering or pore blockage may render these zeolitesineffective for certain catalytic conversions. Twelve-membered rings donot generally appear to offer advantageous conversion catalysts,although structures can be conceived, due to pore blockage or othercause, that may be suitable for use in the present invention.

The Constraint Index provides a convenient indication of the extent towhich a zeolite provides this restrained access. A method fordetermining Constraint Index, together with values of the Index forexemplary zeolites, is described in U.S. Pat. No. 4,016,218 and J.Catalysis 67, 218-222 (1981) to which reference is made for details ofthe method. Because Constraint Index is a characteristic which isdependent upon the structure of the zeolite but is measured by means ofa test which is dependent upon the cracking or acid activity of thezeolite, the test candidate should be representative of the zeolite instructure and have adequate cracking activity. Cracking activity may bevaried by known artifices such as steaming, base exchange or variationof the silica:alumina ratio.

Zeolites which may be treated by the present activation process includethose having the structure of ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35,ZSM-38 and other similar materials having the appropriatecharacteristics. ZSM-5 is described in U.S. Pat. No. 3,702,886; ZSM-11in U.S. Pat. No. 3,709,979; ZSM-12 in U.S. Pat. No. 3,832,449; ZSM-23 inU.S. Pat. No. 4,076,842; ZSM-35 in U.S. Pat. No. 4,016,245 and ZSM-38 inU.S. Pat. No. 4,046,859; said patents incorporated herein by reference.These are preferred zeolites, and of these ZSM-5 is particularlypreferred.

Highly siliceous forms of ZSM-5 are described in U.S. Pat. Re. No.29,948, highly siliceous forms of ZSM-11 in U.S. patent application Ser.Nos. 003,143 (published as Canadian Pat. No. 1,139,733) and 003,145(published as Canadian Pat. No. 1,139,732), filed Jan. 15, 1979 andhighly siliceous forms of ZSM-12 in U.S. patent application Ser. Nos.003,144 (published as Canadian Pat. No. 1,139,731) and 003,146, filedJan. 15, 1979, said descriptions incorporated herein by reference. Allthe foregoing applications are now abandoned.

When the zeolites are prepared in the presence of organic cations theyare initially catalytically inactive, possibly because theintracrystalline free space is occupied by organic cations from theforming solution. They may be activated by heating in an inertatmosphere at 1000° F. (538° C.) for one hour, for example, followed bybase exchange with ammonium salts followed by calcination at 1000° F.(538° C.) in air. The presence of organic cation in the forming solutionmay not be absolutely essential to the formation of the zeolite butthese cations do appear to favor the formation of the desired crystalstructure.

Natural zeolites may sometimes be converted to the desired zeolite, i.e.a zeolite having the described silica to alumina ratio by variousactivation procedures and other treatments such as base exchange,steaming, alumina extraction and calcination. Natural minerals which maybe so treated include ferrierite, brewsterite, stilbite, dachiardite,epistilbite, heulandite, and clinoptilolite.

According to a preferred aspect of the present invention, the preferredzeolites have a crystal framework density, in the dry hydrogen form, notsubstantially below about 1.6 grams per cubic centimeter. The drydensity for known structures may be calculated from the number ofsilicon plus aluminum atoms per 100 cubic Angstroms, as given, e.g., onpage 19 of the article on Zeolite Structure by W. M. Meier, including in"Proceedings of the Converence on Molecular Sieves, London, April 1967",published by the Society of Chemical Industry, London, 1968. When thecrystal structure is unknown, the crystal framework density may bedetermined by classical pyknometer techniques. For example, it may bedetermined by immersing the dry hydrogen form of the zeolite in anorganic solvent which is not sorbed by the crystal.

Crystal framework densities of some typical zeolites are disclosed inEuropean Patent Application No. 34444, corresponding to U.S. Pat. No.4,326,994, each incorporated herein by reference.

When it has been synthesized in the alkali metal form, the zeolite maybe converted to the hydrogen form, generally by intermediate formationof the ammonium form by ammonium ion exchange and calcination ofammonium form to yield the hydrogen form. In addition to the hydrogenform, other forms of the zeolite wherein the original alkali metal hasbeen reduced to less than about 1.5 percent by weight may be used. Thus,the original alkali metal of the zeolite or introduced hydrogen cationsmay be replaced by ion exchange with other suitable ions of Groups IB toVIII of the Periodic Table, including, by way of example, nickel,cadmium, copper, zinc, palladium, calcium or rare earth metals.

It is normally preferred to use zeolites of large crystal size, that is,of about 0.1 micron or larger as opposed to small crystal zeolites ofabout 0.02 to 0.05 micron crystal size because the large crystalzeolites respond better to steaming.

The zeolite, preferably in the as-synthesized form, is composited withan activating metal oxide which is capable of activating the zeolite bythe creation of additional active sites when the zeolite/oxide compositeis steamed. The oxide will normally act as a binder for the zeolite. Thepreferred binder is alumina, preferably in the form of alpha-alumina oralpha-alumina monohydrate but other binders may also be used either ontheir own or in combination with alumina, for example, silica-alumina,silica-zirconia, silica-thoria, silica-berylia, silica-titania as wellas ternary compositions such as silica-alumina-thoria,silica-alumina-zirconia, silica-alumina-magnesia orsilica-magnesia-zirconia. Other metal oxides which may be employedinclude titania, zirconia and chromia. Simple experiment may be employedto determine other useful materials.

The relative proportions of zeolite and binder will generally beadjusted in accordance with the silica to alumina ratio of the zeolite,with the zeolites of higher silica to alumina ratio being able tobenefit more from a larger proportion of binder than those with a lowerratio. In general, the amount of binder will be from 10 to 90 percent bycomposite weight of the combined zeolite and binder, preferably 20 to 80percent by weight. For example, a zeolite with a silica to alumina ratioof about 1600:1 can usefully be composited with 25 to 50 percent byweight of alumina binder.

The zeolite is composited with the binder by intimately mixing the twomaterials together, in the presence of water, after which the mixture isformed into suitable particles and dried. It has been found that thedesired enhancement of activity does not occur if the zeolite and binderare simply mixed dry together instead of being intimately wet mixed asdescribed above. The finely ground mixture of zeolite, binder and watermay conveniently be formed into particles by extrusion using anextrusion press or, alternatively, other shaping methods may be usedsuch as pelletizing or pressing. The amount of water is chosen as togive a mixture which has a satisfactory consistency for the formingstep. The zeolite may contain sufficient occluded water or sufficientwater may be present in the binder.

The zeolite may be treated to convert it to the desired form eitherbefore or after it is composited with the binder. Thus, if it issynthesized in the alkali metal form it may be converted to the hydrogenor another cationic form e.g. the alkali metal, alkaline earth metal orammonium form before or after compositing with the binder. If theconversion entails more than one step the requisite steps may, ifdesired, be carried out at different stages of the process, some beforecompositing and some after. Generally, however, the zeolite should be atleast partly in the hydrogen form during the steaming or, alternatively,in a form which will be wholly or partly converted to the hydrogen formunder the conditions employed during the steaming, e.g. the ammoniumform or the alkylammonium form.

After the zeolite/binder composite has been formed it is subjected tosteaming. During this step, the composite is held in an atmosphereentirely or partly of steam at an elevated temperature. Generally, it ispreferred to operate with an atmosphere of 100% steam although partialsteam atmospheres may also be used with some loss of effectiveness. If agas other than steam is present it should be an inert gas such asnitrogen. The steaming is generally carried out by heating the intimatecomposite mixture in the presence of water at a temperature from 200° to500° C., preferably from 300° to 450° C. Good results have been obtainedat about 400° to 425° C. The pressure during steaming will normally beatmospheric or superatmospheric pressure, generally in the range of 100to 500 kPa, preferably from 100 to 200 kPa or more. The steaming shouldgenerally be continued for at least one hour and usually durations of 12to 48 hours will be preferred.

The steam may be produced in-situ, for example, by the dehydration ofalcohols such as methanol, ethanol, propanol, n-butanol or pentanol toproduce the steam, with olefins as a by-product or by the combustion ofhydrocarbons to produce carbon oxides and steam.

The activity of the catalyst is measured in terms of its alpha value.The alpha value reflects the relative activity of the catalyst withrespect to a high activity silica-alumina cracking catalyst. Todetermine the alpha value, n-hexane conversion is determined at asuitable temperature between about 550° F. to 1000° F. (288° to 538°C.), preferably at 1000° F. (538° C.). Conversion is varied by variationin space velocity such that a conversion level of up to about 60 percentof n-hexane is obtained and converted to a rate constant per unit volumeof zeolite and compared with that of silica-alumina catalyst which isnormalized to a reference activity of 1000° F. (538° C.). The catalyticactivity of the catalyst is then expressed as multiple of this standard,i.e. the silica-alumina standard. The silica-alumina reference catalystcontains about 10 weight percent Al₂ O₃ and the remainder SiO₂. Thismethod of determining alpha, modified as described above, is describedin the Journal of Catalysis, Vol. VI, pages 278-287, 1966, to whichreference is made for further details of the method.

The extent of the activation produced by the present method is notable.Increases of over 100 percent of the alpha value may be obtained withzeolites having a silica to alumina ratio of 1200:1 or more.Commensurate results may be obtained with other zeolites of differingsilica to alumina ratio. The enhancement in activity is believed to becaused by the creation of additional, stable active internal sites inthe zeolite because after the steaming treatment is completed, theConstraint Index remains consistent with that of the original zeolitestructure although the alpha value has increased significantly. Thecatalyst therefore retains its original selectivity but with an improvedacid activity.

The following Examples illustrate the improvement of the presentinvention.

EXAMPLES EXAMPLE 1

A sample of zeolite ZSM-5 in the hydrogen form and having a structuralsilica:alumina ratio of 1600:1 is mulled by ball milling with 35 percentby weight of alpha-alumina monohydrate, adding sufficient deionizedwater to form a mixture which could be conveniently mulled. The mull isextruded into pellets (small cylinders of 1.6 mm diameter) and thepellets air dried at 110° C., precalcined in nitrogen at about 540° C.after which the zeolite is converted to the hydrogen form by ammoniumcation exchange, air drying at about 110° C. and calcination in air atabout 540° C. The alpha value of this catalyst is increased.

A sample of the catalyst is contacted with 100 percent steam atatmospheric pressure and at a temperature of 425° C. for 18 hours. Thesteam treated product has an alpha value which is further increased.After the measurement of the alpha value had been made, the catalyst isregenerated by heating in air to 540° C. The alpha value of theregenerated catalyst is not significantly reduced by the regeneration.

EXAMPLE 2

HZSM-5 extrudate was prepared by mulling 1600:1 as-synthesized ZSM-5with 35% alpha-alumina monohydrate with added deionized water, extruded(1/16 inch), dried at 110° C., precalcined in nitrogen at 538° C.,ammonium exchanged, air dried at 110° C. and then calcined in air at538° C. The alpha value of this catalyst was 7.7.

A sample of this catalyst was contacted with 100% steam at oneatmosphere and 800° F. for 18 hours. The steam treated product was foundto have an alpha value of 17.6. After alpha measurement the catalyst wasair regenerated at 1000° F. Regeneration at 1000° F. gave an alpha valueof 17.4. A Constraint Index (C.I.) of 1.6 at 850° F. was obtained forthe steamed extrudate. The C.I. value obtained is consistent withconventional ZSM-5 catalysts, indicating that the enhanced activity isdue to additional stable sites formed wthin the internal pores of thezeolite.

EXAMPLE 3

A sample of the binder-free 1600:1 zeolite ZSM-5 used in Example 2 wasobtained in the hydrogen form by ammonium exchange of the air calcinedas-synthesized zeolite, followed by air calcination of the ammoniumZSM-5 at about 540° C. The binder-free zeolite was then treated in 100%steam at atmospheric pressure at 425° C. for varying periods of time,after which the activity of the catalyst was determined. The results areshown in Table I below.

                  TABLE I                                                         ______________________________________                                        Steaming Time                                                                 (Hours)        Alpha Activity                                                 ______________________________________                                         0             6.1                                                             6             7.2                                                            18             7.6                                                            45             7.2                                                            94             7.0                                                            ______________________________________                                    

These results, in comparison with those of Example 2, show that thepresence of the binder is necessary for the activation to occur.

EXAMPLE 4

Two parts of the binder-free 1600:1 zeolite ZSM-5 used in Example 2 inthe hydrogen form produced by the air calcination of the ammonium formzeolite were mixed well with one part of alpha-alumina monohydrate andthe mixture was then pelletized and steamed for 18 hours in 100% steamat atmospheric pressure at 425° C. The alpha value of the steamedcatalyst was 6.7, showing that mere admixture of the zeolite and thebinder is insufficient for activation.

EXAMPLE 5

The 1600:1 zeolite ZSM-5 of the preceding Examples in the ammonium formwas mulled with 35% alpha-alumina monohydrate by ball milling afterwhich the mixture was extruded into 1.6 mm cylindrical pellets. Theextruded catalyst was then dried in air at 120° C., precalcined innitrogen at 540° C., followed by an ammonium exchange, air drying at120° C., air calcination and steaming for 18 hours at 425° C. underatmospheric pressure. The alpha value of the steamed catalyst was 12.3,a substantial increase over the original alpha value of 6.1.

The catalyst was then steamed for an additional hour at 540° C. andunder atmospheric pressure, after which the alpha value was found to be12.1, consistent with a theoretical prediction of 12.0.

EXAMPLE 6

ZSM-5 having a silica to alumina ratio of 70:1 and in the as-synthesizedform was mulled with 35 wt. % alpha-alumina monohydrate and extruded.The extrudate was calcined and ammonium exchanged.

A retained portion of a similarly prepared batch of 70:1 crystals wascalcined, ammonium exchanged and the Bronsted acid site content wasfound to be 0.47 MEQ H/gm, i.e. 0.47 milliequivalents of hydrogen pergram of zeolite. The Bronsted acidity of the extrudate was also found tobe 0.47 MEQ H/gm zeolite. The 70:1 ammonium extrudate is identifiedbelow as Extrudate 1.

The Bronsted acidity of retained portions of the 1600:1 binder-freeammonium form of ZSM-5 from Example 5, and of the 1600:1 ammonium formextrudate (Extrudate 2) from the same example were also determined. Thebinder-free sample was found to have 0.02 MEQ H/gm zeolite, andExtrudate 2, 0.057 MEQ H/gm zeolite.

All of the above determinations of acidity were made by TGA titration.

EXAMPLE 7

Extrudate 1 and Extrudate 2 from Example 6 were calcined in 20% airmixed with 80% nitrogen at a high flow rate to convert the extrudates tothe hydrogen form. Each was then steamed at 800° F. in 1 atm. steam for14.5 hours, after which alpha values and acid site densities wereevaluated. The results are shown in Table II.

                  TABLE II                                                        ______________________________________                                                    Alpha     Bronstead Acidity                                                   Value     (MEQ H/gm zeolite)                                      ______________________________________                                        Untreated Extrudate 1                                                                       254         0.47                                                Hydrothermally-treated                                                                      151         0.33                                                Extrudate 1                                                                   Untreated Extrudate 2                                                                       7.7 (estimated)                                                                           .057                                                Hydrothermally-treated                                                                      15          0.13                                                Extrudate 2                                                                   ______________________________________                                    

EXAMPLE 8

Three samples of ZSM-5 having a silica to alumina mole ratio of 38,000to 1 were treated separately as follows:

The first sample was mixed with alpha-alumina monohydrate to give a 65wt. % zeolite/35 wt. % alumina composition. This mixture was not mulled.The mixture was precalcined in ammonia for 3 hours at 538° C., ammoniumexchanged to provide less than 0.02 wt. % Na and then calcined in airfor 3 hours at 538° C.

The second sample was mulled with sufficient alpha-alumina monohydrateto provide a 65/35 mixture and with water added. The wet mulledcomposition was extruded, precalcined in ammonia for 3 hours at 538° C.,ammonium exchanged to provide less than 0.02 wt. % Na and then calcinedin air for 3 hours at 538° C.

The third sample was mulled with sufficient alpha-alumina monohydrate toprovide a 65/35 mixture without water added. The dry mulled compositionwas then treated exactly as above for the wet mulled composition.

EXAMPLE 9

A feedstock comprising propylene was separately reacted over (1) purecrystal ZSM-5 having a silica to alumina mole ratio of 38,000, (2) thephysical mixture catalyst (first sample preparation) of Example 8, (3)the wet mulled catalyst (second sample preparation) of Example 8 and (4)the dry mulled catalyst (third sample preparation) of Example 8.Reaction conditions for each experiment were 204° C., 4137 kPa propylenepartial pressure, about 1 hr⁻¹ (LHSV) and with hydrogen circulating atabout 6895 kPa.

Results from these reactions after one day on stream are listed in TableIII.

                  TABLE III                                                       ______________________________________                                                        Physical Dry-                                                                 Mixture  Mulled                                                        Pure   With     With     Wet-Mulled                                           Crystals                                                                             Binder   Binder   With Binder                                 ______________________________________                                        C.sub.3.sup.=  conversion,                                                               16       15       16     77                                        wt. %                                                                         Yields, wt. %                                                                 C.sub.1 + C.sub.2                                                                        0.1      0.5      0.1    0.3                                       C.sub.3.sup.=                                                                            84.0     85.5     83.6   22.7                                      C.sub.3    7.9      13.3     3.3    2.4                                       C.sub.4 + C.sub.5                                                                        8.0      0.7      8.2    3.0                                       C.sub.6.sup.+                                                                            <0.1     <0.1     4.8    71.9                                                 100.0    100.0    100.0  100.0                                     330° F..sup.+                                                                              --       --     56                                        Distillate,                                                                   % of Liq. Product                                                             ______________________________________                                    

In the absence of the alumina binder, the activity of pure crystal waslow giving 16% conversion, mostly to light products. A dry, physicalmixture of zeolite crystal with the alumina or dry mulling with thealumina showed no activity enhancement. However, when the mixture waswet mulled, a substantial increase in activity was observed. Conversionincreased to 77%, yielding 71.9% liguids containing 56% 330° F.+distillate range products.

What is claimed is:
 1. A process for converting a feedstock comprisingC₂ ⁺ olefins, C₂ -C₇ paraffins or a mixture thereof to conversionproduct comprising C₅ ⁺ hydrocarbon compounds which comprises contactingsaid feedstock at conversion conditions sufficient to convert saidfeedstock to said product with a catalyst composition prepared by amethod which comprises forming a composite of a crystalline zeolitehaving a silica:alumina mole ratio of at least 100:1 and a ConstraintIndex from 1 to 12, a binder comprising alumina, and water, andcontacting the composite with steam to enhance the activity of thecatalyst.
 2. The process of claim 1 in which the zeolite has asilica:alumina ratio of at least about 250:1.
 3. The process of claim 2in which the zeolite has a silica:alumina ratio of at least 1200:1. 4.The process of claim 1 in which the zeolite has the structure of ZSM-5,ZSM-11, ZSM-12, ZSM-23, ZSM-35 or ZSM-38.
 5. The process of claim 4 inwhich the zeolite has the structure of ZSM-5.
 6. The process of claim 1in which the zeolite is in the as-synthesized or in the hydrogen formand the composite is formed by mulling the zeolite and the bindertogether in the presence of water and forming catalyst particles byextruding the mulled wet mixture.
 7. The process of claim 6 in which thezeolite has the structure of ZSM-5 having a silica:alumina ratio of atleast about 250:1 and the binder is alumina.
 8. The process of claim 7in which the zeolite is in the hydrogen form during the contact with thesteam or in a form which is at least partly converted to the hydrogenform by contact with the steam.
 9. A process for converting a feedstockcomprising C₂ ⁺ olefins, C₂ -C₇ paraffins or a mixture thereof toconversion product comprising C₅ ⁺ hydrocarbon compounds which comprisescontacting said feedstock at conversion conditions sufficient to convertsaid feedstock to said product with a catalyst composition prepared by amethod which comprises mixing a high-silica zeolite having a ConstraintIndex of 1 to 12 with a binder comprising alumina, and treating themixture of zeolite and binder at elevated temperature under conditionseffective to increase catalytic activity of said mixture.
 10. Theprocess of claim 9 wherein said metal binder is alumina, said mixturecomprises from about 10 to about 90 weight percent of said alumina, andsaid conditions effective to increase activity include a temperature ofat least about 400° C.
 11. The process of claim 1 wherein saidconversion conditions include a temperature of from about 100° C. toabout 700° C., a pressure of from about 10 kPa to about 11000 kPa, aliquid hourly space velocity of from about 0.1 hr⁻¹ to about 500 hr⁻¹and a hydrogen/hydrocarbon mole ratio of from 0 to about
 20. 12. Theprocess of claim 9 wherein said conversion conditions include atemperature of from about 100° C. to about 700° C., a pressure of fromabout 10 kPa to about 11000 kPa, a liquid hourly space velocity of fromabout 0.1 hr⁻¹ to about 500 hr⁻¹ and a hydrogen/hydrocarbon mole ratioof from 0 to about
 20. 13. The process of claim 1 wherein said feedstockcomprises C₂ -C₇ olefins.
 14. The process of claim 9 wherein saidfeedstock comprises C₂ -C₇ olefins.
 15. The process of claim 13 whereinsaid feedstock comprises propylene.
 16. The process of claim 14 whereinsaid feedstock comprises propylene.
 17. The process of claim 13 whereinsaid zeolite has the structure of ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35or ZSM-38.
 18. The process of claim 14 wherein said zeolite has thestructure of ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35 or ZSM-38.
 19. Theprocess of claim 13 wherein said conversion conditions include atemperature of from about 190° C. to about 375° C., a pressure of fromabout 400 kPa to about 11000 kPa and a liquid hourly space velocity offrom about 0.3 hr⁻¹ to about 2 hr⁻¹.
 20. The process of claim 19 whereinsaid conversion conditions include a temperature of from about 190° C.to about 315° C., a pressure of from about 4200 kPa to about 11000 kPaand a liquid hourly space velocity of from about 0.3 hr⁻¹ to about 1hr⁻¹.
 21. The process of claim 19 wherein said conversion conditionsinclude a temperature of from about 230° C. to about 375° C., a pressureof from about 400 kPa to about 4700 kPa and a liquid hourly spacevelocity of from about 0.3 hr⁻¹ to about 2 hr⁻¹.